1. Field of the Invention
The invention is in the field of filtering and frequency shaping electromagnetic signal processing devices.
2. Brief Description of the Prior Art
Filters of a class known as transversal filters include a length of transmission line each with a series of high impedance taps to extract signal information from the line without inordinate disturbance of the transmission path. The signal from each tap is individually adjusted (attenuated or amplified) such that, when brought together in a summing amplifier, this composite processor possesses the desired frequency response between the input to the transmission line and the output of the amplifier. (N. Weiner et al, U.S. Pat. No. 2,024,900, issued Dec. 17, 1935; H. E. Kallman, Proceedings of the IRE, 28 (1940)302). These signal processors and processing filters are extremely flexible in use and many can be automatically adjusted with electronically variable amplifiers in the taps. Such devices are extensively used, for example, in communications systems (H. Rudin, Jr. IEEE Spectrum (January 1967)53). These processors are particularly well suited for communications uses involving transmission paths (e.g., radio links) with time varying distortions and transmission paths (e.g., coaxial cables) which require processor adjustment in the field. Such processors tend to be relatively complex and expensive but are well worth the cost in situations where their extreme flexibility and adaptiveness is necessary.